The Canadian Province of Alberta has put a cap on how much power can be generated by wind until solutions for wind-variability are in place.

Wind power has become a key part of Canada’s energy mix, with the number of installed wind turbines growing exponentially in recent months. But the fact the wind doesn’t blow all the time is creating a potential roadblock that could stall growth in the industry.

Alberta and Ontario, the two provinces with the most wind turbines up and whirling, face concerns that there are limits on how much power can be generated from the breeze before their electricity systems are destabilized.

Alberta recently put a temporary cap on wind generation at 900 megawatts — a level it could reach as early as next year — because of the uncertainty. And a report in Ontario released last week says that in some situations more than 5,000 MW of wind power, stable operation of the power grid could be jeopardized.

Warren Frost, vice-president for operations and reliability at the Alberta Electric System Operator, said studies done over the past couple of years showed there can be problems when wind contributes more than about 10 per cent of the province’s electricity — about 900 MW — because of the chance the wind could stop at any time.

Each 100 MW of wind power is enough to supply a city about the size of Lethbridge, Alta.

If the power “disappears on you when the wind dies, then you’ve got to make it up, either through importing from a neighbouring jurisdiction or by ramping up generators,” Mr. Frost said.

But Alberta is limited in its imports, because the provincial power grid has connections only with British Columbia and Saskatchewan. And hydroelectric plants with water reservoirs, which can turn on a dime to start producing power, are limited in the province. Coal-fired plants and most gas-fired plants take time to get up to speed, making them less useful as backups when the wind fails.

There can also be a problem, Mr. Frost noted, when the wind picks up and generates more power than is being demanded — that potential imbalance also has to be accounted for.

There are a number of ways to allow wind power to make up a greater proportion of the electricity supply, but they require more study, Mr. Frost said. First, he said, the province can develop more sophisticated ways of forecasting the wind so the power it generates is more predictable.

The province could also build more plants that can quickly respond if the wind dies down during a peak period, for example. But building new gas-powered plants merely to help handle the variability of wind is certain to raise the ire of environmentalists.

The province could also increase its connections to other jurisdictions, where it would buy surplus power when needed. Alberta is already looking at links with some northwestern U.S. states, including Montana.

Over all, Alberta is committed to “adding as much wind as feasible” Mr. Frost said. “What we’re balancing is the reliability [issue].”

Robert Hornung, president of the Canadian Wind Energy Association, which represents companies in the wind business, said he prefers to think of Alberta’s 900 MW limit as a “speed bump” rather than a fixed cap.

“We have every confidence they’ll be able to go further than that,” Mr. Hornung said, particularly if the industry and regulators put some effort into wind forecasting over the next year or so. That’s crucial, he said, because “we have projects of many, many more megawatts than 900 waiting to proceed in Alberta.”

In Ontario, the situation is less acute than in Alberta, but the wind study released last week — prepared for the industry and regulators — shows some similar concerns.

While wind power could be handled by the Ontario grid up to 5,000 MW — about 320 MW of wind turbines are currently in operation with another 960 MW in planning stages — the situation changes at higher levels, the study suggests.

Particularly during low demand periods when wind makes up a relatively high proportion of the power mix, “stable operation of the power system could be compromised” if backup systems can’t be ramped up quickly to deal with wind fluctuations, the report said.

But Ontario is in a better position than Alberta because it has far more interconnections with other provinces and states, where it can buy or sell power.

And it also has its wind turbines more geographically dispersed than Alberta, where most wind farms are in the south of the province. That means the chance of the wind failing everywhere at the same time is lower in Ontario.

Don Tench, director of planning and assessments for Ontario’s Independent Electricity System Operator, said he thinks better wind forecasting is the key to making the new source of power work effectively.

“If we have a few hours notice of a significant wind change, we can make plans to deal with it,” he said.

Mr. Frost, of the Alberta system operator, said European countries such as Denmark and Germany have been able to maintain a high proportion of wind power in their electricity systems mainly because they have multiple connections to other countries’ power grids. That gives them substantial flexibility to import or export power to compensate for wind fluctuation.

Germany, for example, has 39 international interconnections, he said, making variable wind conditions much easier to manage. RICHARD BLACKWELL, Globe and Mail

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